The present invention relates to apparatus for segregating lighter fractions from heavier fractions of suspensions of such fractions in water or another liquid carrier. More particularly, the invention relates to apparatus which can be used with advantage to separate fibers from heavier contaminants in suspensions which contain the constituents of waste paper or the like. Still more particularly, the invention relates to improvements in apparatus wherein the segregation of lighter fraction from heavier fraction is effected by several centrifugal separators of the type known as hydrocyclones, centricleaners, vortex pressure drop type cleaners, tubular gravity separators and conical gravity separators.
It is already known to treat the constituents of a suspension in an apparatus wherein two or more centrifugal separators with tangential inlets for suspension receive the suspension from a first chamber and discharge the lighter fraction into a second chamber. The heavier fraction is evacuated by way of centrally located outlets of the separators. Reference may be had to German Utility Model No. 1,932,636 which discloses a single vessel with a first chamber which feeds the suspension to the tangential inlets of several separators and a second chamber which receives the lighter fraction from upwardly extending outlets of the separators. The vessel is a one-piece casting. Such castings can be produced at a reasonable cost only in relatively small sizes so that the output of apparatus utilizing vessels of the type disclosed in the German Utility Model is relatively low.
German Pat. No. 1,517,945 discloses a modified apparatus wherein the conical housings of several hydrocyclones are attached to the bottom wall of a first chamber which receives the suspension at elevated pressure. The centrally located outlets of the hydrocyclones extend upwardly through the first chamber and discharge the lighter fraction into a second chamber above the first chamber. These outlets are permanently affixed to the bottom of the second chamber. A drawback of the patented apparatus is that the cyclones cannot be detached from the chambers.